The present invention relates to a pressure pump for drawing and delivering by pressure a high viscosity fluid such as adhesive, silicon, grease, printing ink or the like from a can such as drum can, a pail can or the like.
Heretofore, there has been known a pressure pump for high viscosity fluid in which, in order to draw and deliver by pressure a high viscosity fluid stored in a drum can or a pail can therefrom, a follow plate unit for sealing an upper surface of the drum can or the pail can so as to apply pressure to the high viscosity fluid stored therein is attached to a lower end of a transport pipe capable of being moved up-and-down with respect to the drum can or the pail can.
This conventional pressure pump for high viscosity fluid is configured such that, when the high viscosity fluid is to be drawn out of the drum can or the pail can, the follow plate unit is moved downward to seal a fluid surface of the high viscosity fluid and to apply pressure thereto, and at the same time an air pump is actuated to draw the high viscosity fluid from the can, and when the high viscosity fluid is completely drawn out of the drum can or the pail can, the follow plate unit is moved upward to be retracted therefrom (see, for example, Japanese Patent Laid-open Publication No. 82282 of 1996, Japanese Patent Registration No. 2545679).
This type of pressure pump for high viscosity fluid has problems that, if an outer end face of the follow plate unit is not brought into tight-contact with a wall inner surface of the drum can or the pail can, the high viscosity fluid is leaked out upward from a clearance between the outer end face of the follow plate unit and the wall inner surface when the follow plate unit is moved downward to apply pressure to the high viscosity fluid and accordingly the high viscosity fluid cannot be drawn therefrom efficiently, and that, if the outer end face of the follow plate unit is brought into excessive tight-contact with the wall inner surface of the drum can or the pail can, a contact resistance therebetween increases too much when the follow plate unit is to be disengaged from the drum can or the pail can and thereby the follow plate unit is lifted up together with the drum can or the pail can when the follow plate unit is retracted therefrom because of too large contact resistance therebetween. Conventionally, the follow plate unit for the drum can is configured such that an outer diameter of the follow plate unit extend when it is moved downward and is contracted when moved upward.
However, since the conventional follow plate unit for the drum can is configured so as for the outer diameter thereof to be contracted by own weight, there occurs a problem that the outer diameter of the follow plate unit cannot be contracted promptly when the follow plate unit having reached down to a bottom of the drum can is moved upward to be retracted from the drum can and as a result, the follow plate unit is lifted up together with the drum can because of the large contact resistance therebetween.
In order to solve the above problems, there has been developed an improved pressure pump for high viscosity fluid which allows the follow plate unit to be smoothly retracted from the drum can without deteriorating a sealing capacity for drawing the high viscosity fluid out of the drum can (see Japanese Patent Application No. 118469 of 1999, filing date: Apr. 26 of 1999).
The Japanese Patent Application No. 118469 of 1999 discloses the pressure pump for high viscosity fluid, in which a follow plate unit is composed of a lower plate attached to a transport pipe and an upper plate mounted on said lower plate so as to be capable of being moved up-and-down with respect thereto, wherein said lower plate is provided with a pressure disc for being brought into contact with the high viscosity fluid to apply pressure thereto, and said upper plate is provided with an annular elastic sealing member whose outer periphery is provided with a sealing contact portion which is engaged with an outer periphery of the pressure disc and whose outer end face is brought into contact with a wall inner surface of a drum can to make a sealing, and said lower plate is further provided with a plurality of air cylinders as an up-and-down driving member for moving up or down the upper plate, which moves the upper plate downward so that an outer diameter of the annular elastic sealing member may be extended when the high viscosity fluid stored in the drum can is to be drawn and delivered by pressure from the drum can and moves the upper plate upward so that the outer diameter of the annular elastic sealing member may be contracted when the follow plate unit is to be retracted from the drum can.
However, since the pressure pump for high viscosity fluid disclosed by the Japanese Patent Application No. 118469 of 1999 is configured such that each of the plurality of air cylinders is attached to the lower plate, the structure thereof is rather complicated and an assembling operation thereof is also rather troublesome.
The present invention is achieved in the light of the situation described above, and an object thereof is to provide an innovative pressure pump for high viscosity fluid which allows the follow plate unit to be smoothly retracted from the drum can without deteriorating a sealing capacity for drawing the high viscosity fluid out of the drum can and also allows an assembling operation thereof to be performed easily.
The invention defined by claim 1 provides a pressure pump for high viscosity fluid in which, in order to draw and deliver by pressure a high viscosity fluid stored in a can therefrom, a follow plate unit for sealing an upper surface of said can to apply pressure to said high viscosity fluid stored therein is attached to a lower end of a transport pipe capable of being moved up-and-down with respect to said can, said pressure pump characterized in that said follow plate unit comprises a follow plate body having a guide passage for high viscosity fluid, a cylinder fitted on an outer surface of said follow plate body so as to be capable of being moved upward and downward along a vertical direction, an upper plate attached to said cylinder so as to be capable of being moved upward and downward along therewith, a lower plate attached to a lower portion of said follow plate body, and a ring type elastic sealing member interposed between said upper plate and said lower plate, wherein a pressure chamber for making a compressed air flow in-and-out is provided between said follow plate body and said cylinder, a compressed air inlet/outlet port is provided on said cylinder so as to communicate with said pressure chamber, said ring type elastic sealing member comprises an upper ring type elastic sealing member and a lower ring type elastic sealing member, said lower ring type elastic sealing member is fixed to said lower plate, said upper ring type elastic sealing member is fixed to said upper plate, said upper ring type elastic sealing member and said lower ring type elastic sealing member are bonded with each other at outer peripheral portions thereof to be formed into a contact portion which is to be brought into contact with a wall inner surface of said can, and an outer diameter of said ring type elastic sealing member is extended or contracted by flow-in or flow-out of the compressed air to or from said pressure chambers.
The invention defined by claim 2 provides a pressure pump for high viscosity fluid in accordance with that defined by claim 1, said pressure pump further characterized in that a liner cylinder for guiding said cylinder along a vertical direction is inserted between said follow plate body and said cylinder, and an annular flange for partitioning said pressure chamber into an upper pressure chamber and a lower pressure chamber is formed on an outer surface of said liner cylinder.
The invention defined by claim 3 provides a pressure pump for high viscosity fluid in accordance with that defined by claim 2, said pressure pump further characterized in that said cylinder has a bottom cylinder sealing ring and a top cylinder sealing ring, an annular groove for receiving O-ring is formed on an inner surface of each of said bottom and said top cylinder sealing rings, an O-ring is fitted into each of said annular grooves for receiving O-ring in order to seal said compressed air within said pressure chamber, and another annular groove for receiving O-ring is formed on said annular flange, into which an O-ring is fitted for preventing a leakage of said compressed air from said upper pressure chamber to said lower pressure chamber.